include

using namespace std;

int main() {

int n;
double m, a, b, c, d;
scanf("%d", &n);
for (int i = 1; i <= n; i++) {
	scanf("%lf%lf%lf%lf", &a, &b, &c, &d);
	m = (a * c) / (b * d);
	printf("%.6lf\n", m);
}
return 0;

}